?
bool
$associative
=
null
,
int
$depth
= 512
,
int
$flags
= 0
):
mixed
JSON エンコードされた文字列を受け取り、それを
PHP の値に変換します。
true
の場合、返されるオブジェクトは連想配列形式になります。
false
の場合、返されるオブジェクトは
object
になります。
null
の場合、返されるオブジェクトは
flags
に
JSON_OBJECT_AS_ARRAY
が設定されているかどうかによって、
連想配列形式か
object
かが変化します。
例1
json_decode()
の例
<?php
$json
=
'{"a":1,"b":2,"c":3,"d":4,"e":5}'
;
var_dump
(
json_decode
(
$json
));
var_dump
(
json_decode
(
$json
,
true
));
?>
object(stdClass)#1 (5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
array(5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
例3
json_decode()
でのありがちな間違い
<?php
// 以下の文字列は JavaScript としては有効ですが JSON としては無効です
// 名前と値はダブルクォートで囲む必要があります。
// シングルクォートは使えません
$bad_json
=
"{ 'bar': 'baz' }"
;
json_decode
(
$bad_json
);
// null
// 名前をダブルクォートで囲まなければなりません
$bad_json
=
'{ bar: "baz" }'
;
json_decode
(
$bad_json
);
// null
// 最後にカンマをつけてはいけません
$bad_json
=
'{ bar: "baz", }'
;
json_decode
(
$bad_json
);
// null
?>
例4
depth
エラー
<?php
// データをエンコードします。ネストの深さは4です (array -> array -> array -> string)
$json
=
json_encode
(
array(
1
=> array(
'English'
=> array(
'One'
,
'January'
),
'French'
=> array(
'Une'
,
'Janvier'
)
)
)
);
// さまざまな深さのエラーを表示します
var_dump
(
json_decode
(
$json
,
true
,
4
));
echo
'Last error: '
,
json_last_error_msg
(),
PHP_EOL
,
PHP_EOL
;
var_dump
(
json_decode
(
$json
,
true
,
3
));
echo
'Last error: '
,
json_last_error_msg
(),
PHP_EOL
,
PHP_EOL
;
?>
array(1) {
array(2) {
["English"]=>
array(2) {
string(3) "One"
string(7) "January"
["French"]=>
array(2) {
string(3) "Une"
string(7) "Janvier"
Last error: No error
Last error: Maximum stack depth exceeded
例5
json_decode()
で大きな整数値を扱う例
<?php
$json
=
'{"number": 12345678901234567890}'
;
var_dump
(
json_decode
(
$json
));
var_dump
(
json_decode
(
$json
,
false
,
512
,
JSON_BIGINT_AS_STRING
));
?>
object(stdClass)#1 (1) {
["number"]=>
float(1.2345678901235E+19)
object(stdClass)#1 (1) {
["number"]=>
string(20) "12345678901234567890"
Lennart Hengstmengel
¶
1 year ago
JSON can be decoded to PHP arrays by using the $associative = true option. Be wary that associative arrays in PHP can be a "list" or "object" when converted to/from JSON, depending on the keys (of absence of them).
You would expect that recoding and re-encoding will always yield the same JSON string, but take this example:
$json = '{"0": "No", "1": "Yes"}';
$array = json_decode($json, true); // decode as associative hash
print json_encode($array) . PHP_EOL;
This will output a different JSON string than the original:
["No","Yes"]
The object has turned into an array!
Similarly, a array that doesn't have consecutive zero based numerical indexes, will be encoded to a JSON object instead of a list.
$array = [
'first',
'second',
'third',
];
print json_encode($array) . PHP_EOL;
// remove the second element
unset($array[1]);
print json_encode($array) . PHP_EOL;
The output will be:
["first","second","third"]
{"0":"first","2":"third"}
The array has turned into an object!
In other words, decoding/encoding to/from PHP arrays is not always symmetrical, or might not always return what you expect!
On the other hand, decoding/encoding from/to stdClass objects (the default) is always symmetrical.
Arrays may be somewhat easier to work with/transform than objects. But especially if you need to decode, and re-encode json, it might be prudent to decode to objects and not arrays.
If you want to enforce an array to encode to a JSON list (all array keys will be discarded), use:
json_encode(array_values($array));
If you want to enforce an array to encode to a JSON object, use:
json_encode((object)$array);
See also:
https://www.php.net/manual/en/function.array-is-list.php
greaties at ghvernuft dot nl
¶
7 months ago
To load an object with data in json format:
(bugfixed my previous comment)
<?php
function
loadJSON
(
$Obj
,
$json
)
{
$dcod
=
json_decode
(
$json
);
$prop
=
get_object_vars
(
$dcod
);
foreach(
$prop
as
$key
=>
$lock
)
{
if(
property_exists
(
$Obj
,
$key
))
{
if(
is_object
(
$dcod
->
$key
))
{
loadJSON
(
$Obj
->
$key
,
json_encode
(
$dcod
->
$key
));
}
else
{
$Obj
->
$key
=
$dcod
->
$key
;
}
}
}
return
$Obj
;
}
?>
Tested with:
<?php
class
Name
{
public
$first
;
public
$last
;
public function
fullname
()
{
return
$this
->
first
.
" "
.
$this
->
last
;
}
}
$json
=
'{"first":"John","last":"Smith"}'
;
$infull
=
loadJSON
((new
Name
),
$json
);
echo
$infull
->
fullname
();
Alien426
¶
2 years ago
Browsers don't choke on integers _starting_ with BigInt (64 bits), but before that (53 bits). The introduction of BigInt to modern browsers doesn't help much, when JSON handling functions do not support it. So I am trying to remedy that. My approach is to handle the decoded array before re-encoding it to a string:
<?php
function
fix_large_int
(&
$value
)
{
if (
is_int
(
$value
) &&
$value
>
9007199254740991
)
$value
=
strval
(
$value
);
}
$json_str
=
'{"id":[1234567890123456789,12345678901234567890]}'
;
$json_arr
=
json_decode
(
$json_str
,
flags
:
JSON_BIGINT_AS_STRING
|
JSON_OBJECT_AS_ARRAY
);
echo(
json_encode
(
$json_arr
));
array_walk_recursive
(
$json_arr
,
'fix_large_int'
);
echo(
json_encode
(
$json_arr
));
?>
cubefox at web dot NOSPAMPLEASE dot de
¶
2 years ago
Warning: As the section "return values" mentions, the return value NULL is ambiguos. To repeat, it can mean three things:
* The input string had the value "null"
* There was an error while parsing the input data
* The encoded data was deeper than the recursion limit
To distinguish these cases, json_last_error() can be used.
greaties at ghvernuft dot nl
¶
2 years ago
To load an object with data in json format:
function loadJSON($Obj, $json)
{
$dcod = json_decode($json);
$prop = get_object_vars ( $dcod );
foreach($prop as $key => $lock)
{
if(property_exists ( $Obj , $key ))
{
if(is_object($dcod->$key))
{
loadJSON($Obj->$key, json_encode($dcod->$key));
}
else
{
$Obj->$key = $dcod->$key;
}
}
}
}
Anonymous
¶
1 year ago
<?php
$array
= [
0
=>
"foo"
,
1
=>
"bar"
,
2
=> [
"baz"
]];
$associative
=
false
;
var_dump
(
json_decode
(
json_encode
(
$array
),
$associative
)
);
?>
The above will output
<?php
?>
Considering
<?php $associative
=
false
;
?>
one might expect
<?php
?>
an stdClass object instead of an array, but this is incorrect.
json_decode will always return an array for a sequentially encoded array, regardless of the ?bool $associative 2nd argument
Which is inline with the above mentioned docs/spec
> Returns the value encoded in json in appropriate PHP type
Considering that the 1st arg was a sequentially encoded array as a json string
'["foo","bar",["baz"]]'
mattia
¶
2 years ago
if you're using ajax to post, and your JavaScript code looks like this:
<code>
var xhttp = new XMLHttpRequest();
xhttp.open("POST", "something.php", true);
xhttp.setRequestHeader("Content-Type", "application/json");
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
// do something
}
};
var data = {some: "thing"};
xhttp.send(JSON.stringify(data));
</code>
then in <code>something.php</code> you can retrieve your json by doing
<?php
$data
=
json_decode
(
file_get_contents
(
"php://input"
),
true
);
?>
